Showing papers by "Tulane University published in 1990"

Zidovudine in Asymptomatic Human Immunodeficiency Virus Infection: A Controlled Trial in Persons with Fewer Than 500 CD4-Positive Cells per Cubic Millimeter

Abstract: Zidovudine (AZT) is a potent inhibitor of the replication of the human immunodeficiency virus (HIV), and it has been shown to improve survival in advanced HIV disease. We conducted a randomized, double-blind trial in adults with asymptomatic HIV infection who had CD4+ cell counts of fewer than 500 per cubic millimeter on entry into the study. The subjects (92 percent male) were randomly assigned to one of three treatment groups: placebo (428 subjects); zidovudine, 500 mg per day (453); or zidovudine, 1500 mg per day (457). After a mean follow-up of 55 weeks (range, 19 to 107), 33 of the subjects assigned to placebo had the acquired immunodeficiency syndrome (AIDS), as compared with 11 of those assigned to receive 500 mg of zidovudine (P = 0.002; relative risk, 2.8; 95 percent confidence interval, 1.4 to 5.6) and 14 of those assigned to receive 1500 mg of zidovudine (P = 0.05; relative risk, 1.9; 95 percent confidence interval, 1.0 to 3.5). In the three treatment groups, the rates of progression (per 100 person-years) to either AIDS or advanced AIDS-related complex were 7.6, 3.6, and 4.3, respectively. As compared with those assigned to placebo, the subjects in the zidovudine groups had significant increases in the number of CD4+ cells and significant declines in p24 antigen levels. In the 1500-mg zidovudine group, severe hematologic toxicity (anemia or neutropenia) was more frequent than in the other groups (P less than 0.0001). In the 500-mg zidovudine group, nausea was the only toxicity that was significantly more frequent (in 3.3 percent) than in the placebo group (P = 0.001). We conclude that zidovudine is safe and effective in persons with asymptomatic HIV infection and fewer than 500 CD4+ cells per cubic millimeter. Additional study will be required to determine whether such treatment will ultimately improve survival for persons infected with HIV.

Eigentensors of linear anisotropic elastic materials

Abstract: In this paper a method of construction of the eigentensors for the anisotropic elastic-material symmetries is presented and applied to determine the eigentensors of each anisotropic elastic symmetry. The eigentensors for the anisotropic symmetries are shown to have the same important properties as those possessed by the eigentensors of isotropic elasticity

Growth responses of tropical shrubs to treefall gap environments

Abstract: To investigate the effects of differences in light and nutrient availability on growth, we planted seven species of shrubs in two genera, Miconia (Melastomataceae) and Piper (Piperaceae), into the centers, edges, and adjacent forest understory of four natural treefall gaps (275-335 M2) in the tropical, premontane rain forest of Costa Rica. We used rooted cuttings of species typical of forest understory environments on the one hand and large clearings or disturbed areas on the other. We also compared growth rates of three Miconia species grown in shade houses under 2, 20, and 40% full sunlight. Both light and nutrient availability in newly formed gaps of these sizes were strongly buffered by the canopy and root systems of the surrounding forest. Total incident radiation was higher in gap centers (9-23% full sunlight) than in gap-forest edges (3-11%) or under intact forest canopy (0.4-2%), but varied among similar microhabitats from different sites. Relative stem growth rates (RGRS) of all field-grown plants were significantly greater in gap centers than at edges or beneath forest understories. Fertilization did not significantly affect growth rate in any light environment. Light appears to be the most critical resource limiting growth at these gap sizes. In general, shade-tolerant species were less plastic than light-demanding species, but at these gap sizes grew as fast or faster in the gap centers. In shade-houses, the shade-tolerant species grew fastest at 20% full sunlight and light-demanding species grew fastest at 40% full sunlight. We found no evidence of a trade-off between growth and foliar phenolic concentration in these species.

Growth Hormone (GH)-Releasing Peptide Stimulates GH Release in Normal Men and Acts Synergistically with GH-Releasing Hormone*

Abstract: The acute GH release stimulated by the synthetic hexapeptide, His-DTrp-Ala-Trp-DPhe-Lys-NH2 [GH releasing peptide (GHRP)], was determined in 18 normal men and compared with the effects of GH-releasing hormone, GHRH-(1-44)-NH2. Specificity of effect was assessed by measurement of serum PRL, LH, TSH, and cortisol. GHRP was administered at doses of 0.1, 0.3, and 1.0 microgram/kg by iv bolus. GHRH at a dose of 1.0 microgram/kg was administered alone and together with various does of GHRP. No adverse clinical effects of laboratory abnormalities were observed in response to GHRP. A side-effect of mild facial flushing of 1- to 3-min duration occurred in 16 of the 18 subjects who received GHRH-(1-44)-NH2. Mean (+/- SEM) peak serum GH levels after injection of placebo and 0.1, 0.3, and 1.0 microgram/kg GHRP were 1.2 +/- 0.3, 7.6 +/- 2.5, 16.5 +/- 4.1, and 68.7 +/- 15.5 micrograms/L, respectively. The submaximal dosages of 0.1 and 0.3 microgram/kg GHRP plus 1 microgram/kg GHRH stimulated GH release synergistically. Serum PRL and cortisol levels rose about 2-fold above basal levels only at the 1 microgram/kg dose of GHRP, and there were no changes in serum LH and TSH over the first hour after administration of the peptide(s). GHRP is a potent secretagogue of GH in normal men. Since GHRP and GHRH together stimulate GH release synergistically, these results suggest that GHRP and GHRH act independently. This supports our hypothesis that the GH-releasing activity of GHRP reflects a new physiological system in need of further characterization in animals and man.

Characterization and Distribution of Binding Sites for the Hypothalamic Peptide, Pituitary Adenylate Cyclase-Activating Polypeptide

Abstract: A novel bioactive peptide was recently isolated from ovine hypothalamus and was named PACAP (pituitary adenylate cyclase-activating polypeptide). PACAP was present in two bioactive, amidated forms, PACAP27 and PACAP38 (27 and 38 amino acids, respectively), and showed a 68% sequence homology with vasoactive intestinal peptide (VIP) in the Nterminal 28 residues. PACAP38 was at least 1000 times more potent than VIP in stimulating adenylate cyclase in pituitary cells, but both peptides exhibited comparable vasodepressor activity. Thus, we sought to determine whether PACAP acts on specific binding sites in the anterior pituitary or other tissues and whether these binding sites are different from those of VIP. Binding of [125I] PACAP27 to freshly prepared rat anterior pituitary membranes in the presence and absence of 212 nM unlabeled PACAP27 was specific, saturable, and more rapid at 22 C than at 4 C. Scatchard analysis of this binding site using increasing doses of unlabeled PACAP27 revealed a single high aff...

Involvement of organum vasculosum of lamina terminalis and preoptic area in interleukin 1 beta-induced ACTH release

Abstract: Intravenous administration of recombinant human interleukin 1 beta (IL-1 beta, 1 micrograms/100 g body wt) resulted in a marked elevation of plasma adrenocorticotropic hormone (ACTH) levels, with peak levels at 10 min, in conscious unrestrained rats. One week after the placement of a lesion by radiofrequency or microinjection of kainic acid in the organum vasculosum of lamina terminalis (OVLT) but not in subfornical organ, ACTH response to intravenous IL-1 beta was enhanced, whereas both radiofrequency-induced lesion and kainic acid in the preoptic area (POA) suppressed the response. Indomethacin or a prostaglandin E (PGE) antagonist microinjected into the OVLT or POA suppressed or abolished the response. On the other hand, PGE, but not PGD2, microinjected into the POA increased plasma ACTH levels. These results suggest an important role for the OVLT, which lacks blood-brain barrier, as a possible site of entry of blood-borne IL-1 beta into the brain and for the POA, which may contain the neurons required for the response. Involvement of PGE in the OVLT and POA in the ACTH response to intravenous IL-1 beta is also suggested.

Immunohistochemical demonstration of a novel hypothalamic peptide, pituitary adenylate cyclase-activating polypeptide, in the ovine hypothalamus.

Abstract: We recently reported isolation, characterization and synthesis of a novel ovine hypothalamic peptide with 38 residues which stimulates accumulation of cAMP in rat anterior pituitary cell cultures. The peptide was named PACAP38 (pituitary adenylate cyclase-activating polypeptide with 38 residues). The presence of another peptide corresponding to the N-terminal 1-27 residues (PACAP27) was also demonstrated. Both PACAP38 and PACAP27 have an amidated C-terminus. Antisera against synthetic PACAP27 were generated in rabbits. These antisera were tested for titer and specificity in enzyme-linked immunosorbent assay. One of the antisera (no. 88121-3) exhibited a high titer of antibody, which was specific to PACAP27 and PACAP38 with exception of slight cross-reactivity with ovine CRF (oCRF). Therefore, the antibodies against oCRF were removed from the antiserum using a solid phase method. Removal of oCRF antibodies was confirmed by enzyme-linked immunosorbent assay. A dense immunoreactive fiber network was found in both external and internal zones of the median eminence and pituitary stalk. The fibers were demonstrated to be in close contact with the hypophysial portal capillaries. The preabsorption of antiserum with vasoactive intestinal polypeptide or with the mixture containing TRH, LHRH, oCRF, ovine GH-releasing factor, somatostatin, and bovine thyroglobulin did not affect the immunostaining. On the other hand, the preabsorption of antiserum with an excess of PACAP27 or PACAP38 abolished the immunostaining. Therefore, the staining is considered specific for PACAP27 and PACAP38. Stained fibers were also present in the posterior pituitary. A dense fiber network was observed and the lateral hypothalamus the fibers appeared to cling to unstained neuronal cell bodies and their dendrites. In the lateral septum the fibers surrounded some blood vessels. Immunolabeled cell bodies were found in the paraventricular and supraoptic nuclei. These findings support the view that PACAP may play a multifunctional role, including that of a hypophysiotropic hormone, neurotransmitter, neuromodulator, and vasoregulator.

Detection of a human intracisternal A-type retroviral particle antigenically related to HIV

Abstract: Sjogren's syndrome is an autoimmune disease that is characterized by dryness of the mouth and eyes. The loss of salivary and lacrimal gland function is accompanied by lymphocytic infiltration. Because similar symptoms and glandular pathology are observed in certain persons infected with human immunodeficiency virus (HIV), a search was initiated for a possible retroviral etiology in this syndrome. A human intracisternal A-type retroviral particle that is antigenically related to HIV was detected in lymphoblastoid cells exposed to homogenates of salivary tissue from patients with Sjogren's syndrome. Comparison of this retroviral particle to HIV indicates that they are distinguishable by several ultrastructural, physical, and enzymatic criteria.

Detection of serum antibodies to retroviral proteins in patients with primary sjögren's syndrome (autoimmune exocrinopathy)

Abstract: Primary Sjogren's syndrome (SS) is considered a benign autoimmune disease; it is characterized by lymphoid infiltration of salivary and lacrimal glands, often accompanied by the presence of serum autoantibodies, particularly anti-Ro (SS-A) and anti-La (SS-B). There are important immunologic similarities between primary SS and acquired immunodeficiency syndrome. To investigate for a possible immune response to retroviral proteins in primary SS, we performed immunoblotting against human immunodeficiency virus-1 (HIV-1) proteins using sera from 47 patients with primary SS. Moderate-to-strong reactivity, suggesting the presence of serum antibodies, was found in 14 patients (30%). Of 120 normal subjects, only 1 showed moderate positivity. All 14 positive SS sera reacted against p24 (gag) but failed to react against gp41 or gp120 (env). This response did not reflect hypergammaglobulinemia since immunoglobulin concentrations among the 29 SS patients studied were the same in sera that contained and sera that did not contain anti-gag reactivity. Two sera also reacted against p17 gag. Four reacted against HIV-2 core proteins, but none reacted with core proteins of human T lymphotropic virus-I. Only 1 of the 14 sera reacted against Ro (SS-A), and 1 other reacted against La (SS-B). These results identify a subset of SS patients characterized by 1) the presence of serum antibodies to HIV-1 group-specific, but not type-specific, proteins, and 2) the relative absence of anti-Ro (SS-A) and anti-La (SS-B) autoantibodies. In this latter respect, these SS patients constitute a subpopulation that resembles patients with HIV-induced SS-like disease.

A survey of running injuries in 1505 competitive and recreational runners.

Abstract: A 33 item multiple choice questionnaire was circulated; completed questionnaires from 1505 runners (1130 male and 375 female) were obtained. Questions focused upon training, injuries sustained, and medical care. Biomechanical imbalances such as leg length inequality appear to be a major contributing factor to running injuries. Correction of an underlying biomechanical defect may be important in the treatment of many running injuries. Female runners were found to be more susceptible than males to stress fractures at higher mileages. The cause of this increased incidence may be attributable to lower bone mineral density levels as a result of hormonal factors. Factors such as running surface, age and stretching techniques do not appear to play a significant part in the pathogenesis of running injuries.

The interview in the admission process.

Abstract: Significant demographic, legal, and educational developments during the last ten years have led medical schools to review critically their selection procedures. A critical component of this review is the selection interview, since it is an integral part of most admission processes; however, some question its value. Interviews serve four purposes: information gathering, decision making, verification of application data, and recruitment. The first and last of these merit special attention. The interview enables an admission committee to gather information about a candidate that would be difficult or impossible to obtain by any other means yet is readily evaluated in an interview. Given the recent decline in numbers of applicants to and interest in medical school, many schools are paying closer attention to the interview as a powerful recruiting tool. Interviews can be unstructured, semistructured, or structured. Structuring involves analyzing what makes a medical student successful, standardizing the questions for all applicants, providing sample answers for evaluating responses, and using panel interviews (several interviewers simultaneously with one applicant). Reliability and validity of results increase with the degree of structuring. Studies of interviewers show that they are often biased in terms of the rating tendencies (for instance, leniency or severity) and in terms of an applicant's sex, race, appearance, similarity to the interviewer, and contrast to other applicants). Training interviewers may reduce such bias. Admission committees should weigh the purposes of interviewing differently for various types of candidates, develop structured or semistructured interviews focusing on nonacademic criteria, and train the interviewers.

Stabilized jellium: Structureless pseudopotential model for the cohesive and surface properties of metals

Abstract: The ions in a simple metal act on the valence electrons via a pseudopotential. The long-range part is represented by the electrostatic potential from the positive background of the jellium model. The short-range part can be simulated by a constant (over the interior of the metal), chosen to stabilize the metal at its observed bulk valence-electron density. In this structureless pseudopotential model, the bulk properties of a metal depend only upon valence z and bulk density parameter ${\mathit{r}}_{\mathit{s}}$, while the surface properties depend upon ${\mathit{r}}_{\mathit{s}}$ alone (an experimental trend heretofore not understood). These properties are calculated in closed analytic form, and the anomalies of the jellium model (negative surface energy for ${\mathit{r}}_{\mathit{s}}$\ensuremath{\approxeq}2; negative bulk modulus for ${\mathit{r}}_{\mathit{s}}$\ensuremath{\approxeq}6) are found to be rectified. The new model, perhaps the simplest one viable for all ${\mathit{r}}_{\mathit{s}}$, may also be used to study interfaces, metallic clusters, vacancies, electromagnetic response, etc. A variant of the model, which simulates the effects of atomic corrugation, predicts the crystal face dependence of surface properties. This dependence is strong for the electron-density profile, but not for the surface energy, work function, and distance from the centroid of excess charge to the first lattice plane. Results are presented for metallic hydrogen as well as for Al, Pb, Zn, Mg, Ca, Li, Sr, Ba, Na, K, Rb, and Cs.

Confessing Excess: Women and the Politics of Body Reduction

Abstract: During the interviews for my dissertation research, which dealt with aerobics, I frequently confronted women’s all encompassing need to lose weight regardless of what their actual size was. This obsession depressed me, but at the same time filled with questions such as: Why do we need to torture ourselves with crazy diets? Why do we need to be thinner? Why do we judge ourselves so hard? And do we merely exercise to control our weight? When I was struggling to find answers to these questions, I discovered Carol Spitzack’s (1990) book Confessing Excess: Women and t.he politics of body reduction. Her theorizing concerning women’s dieting practices was very helpful to me in terms of understanding aerobicizers’ notions ofweight control. Although Spitzack does not directly examine exercise, I believe that her book can be an important resource for anyone studying women and physical activity. For whenever we deal with women’ s physical activity-sport, exercise or dance-we must address such issues as body, physicality, female beauty, and health. I find myself referring back to Spitzack’s text over and over again as I try to come to terms with such themes as female sexuality in physical activity, health as promoted through exercise, or exercise clothing. Although publishedin 1990, Spitzack’s book is still timely and pertinent, therefore, I would like to share it with the other readers of this journal. Spitzack grounds her book in large part on Foucaultian theory of power. Michel Foucault is not interested in pointing out a particular source of power. Rather, he believes that power is unidentified in origin and has a ubiquitous presence. In addition, this power is not openly oppressive, but works through persuasion. Discourses are the means to these persuasions. Discourses dictate what we know about our cultural practices. For example, different discourses tell us about diet., health or beauty. Our knowledge ofthese particular, mainly feminine practices, is learned through the discourses and we learn the “proper” ways of behaving and the proper ways of being a femaie. These proper ways are defined by the dominant powers in society. Spitzack points out, for example, that our understanding of health is defined hhrough a discourse of health, which itself is a combination of the political, economic, and historical forces in society. Through this definition she also aligns herself with feminist perspectives as she assumes that, in part, such discourses are defined by the masculine ideology; one dominant power in this society. In her book she aims to explain how the narrative of dieting

The physics of baseball

Abstract: The illumination of the ordinary—of why the sky is blue or why the stars shine—is not the least important role of physics and physicists. Then can't we add to the list of deeper queries some of the questions that seemed so important to me in my youth: How can Babe Ruth hit so many home runs? What makes Carl Hubble's curveball and screwball swerve in their trips to the plate? And if baseball plays no known role in the fundamental structure of the universe (see The Iowa Baseball Confederacy by W. P. Kinsella for a contrary position), it is not of trivial importance in the perception and appreciation of that universe by some of its inhabitants. Although not quite so important now, in the period between the Civil War and World War II baseball was a significant part of what defined the United States. Forty years ago, Jacques Barzun, a preeminent student of American culture and a native of France, said, “Whoever wants to know… America had better learn baseball.” But, even as the game itself is subtle and comple...

Beneficial effect of enhanced macrophage function in the trauma patient.

Abstract: Host immunosuppression after trauma contributes to septic morbidity. The macrophage is a key element in the host immune response. This study evaluated glucan, a macrophage stimulant, in a prospective, randomized, double-blind study of 38 trauma patients undergoing surgery. Glucan (21 patients), 50 mg/m2, or placebo (17 patients) was given intravenously daily for 7 days. Delayed hypersensitivity skin testing was performed on days 1 and 7 after trauma. Serum interleukin-1 (IL-1) and tumor necrosis factor (TNF) were assayed after trauma. While the total mortality rate was significantly less in the glucan group (0% versus 29%) (p less than 0.05), the mortality rate from sepsis was not statistically different (0% versus 17.6%). Glucan therapy significantly decreased septic morbidity (9.5% versus 49%; p less than 0.05). Serum IL-1 had a greater increase in glucan patients on day 3 after trauma (143.4 +/- 19.3% versus 78.6 +/- 11.7%; p less than 0.05), but there was no difference thereafter. Serum TNF did not vary between groups. Early increase in IL-1 correlated with subsequent skin test conversion to positive. Neither serum IL-1 nor TNF was a reliable indicator of future sepsis. Further clinical trials are indicated to evaluate biologic response modifiers that activate macrophages in the trauma patient.

Synthesis and biological evaluation of prodrugs of zidovudine

Abstract: A series of prodrugs of zidovudine (AZT) has been synthesized in an effort to enhance the uptake of the prodrugs by the HIV-1 infected cells and to increase the plasma half-life of AZT. The 5'-OH function of AZT was esterified with various acids in the presence of DCC and 4-(dimethylamino)pyridine (DMAP). The prodrug moieties included (a) morpholine and N-phenylpiperazine-1-acetic acid, (b) 1,4-dihydro-1-methyl-3-nicotinic acid, (c) retinoic acid, and (d) certain amino acids. The anti-HIV-1 activity of the esters was determined in peripheral blood lymphocytes. The IC50 for AZT in this system was 0.12 microM whereas for prodrugs it ranged from 0.05 to 0.2 microM. The prodrugs were generally less cytotoxic than AZT except the retinoic acid ester. In vitro hydrolysis of the various esters in human plasma indicated that these agents were relatively stable toward plasma esterases with t1/2 ranging from 10 to 240 min. Drug uptake studies in H9 cells with radiolabeled analogues demonstrated that the retinoic acid ester achieved approximately 4-fold higher intracellular concentration than [3H]AZT. However, 1,4-dihydro-1-methyl-3-[(pyridylcarbonyl)oxy] ester (5) was the most active agent of this series and had a higher therapeutic index than AZT.

Nitrogen and phosphorus fertilization of Jamaican montane forest trees

Abstract: Plots in the Jamaican montane forest were fertilized with nitrogen or with phosphorus to test the hypothesis that growth of trees in this natural forest is limited by the supply of N and P from the soil.Once a year from 1983 to 1986, urea was added to one plot (at 150 kg N ha−1 y−1) and triple superphosphate was added to another (at 50 kg P ha−1 y−1). In each of these plots and in two control plots, foliage of four common tree species was collected immediately before each fertilizer addition. Trunk growth was measured in 105 individuals.Foliar N concentrations were not significantly higher in trees fertilized with N compared to control trees. In Dendropanax cf. pendulus and Hedyosmum arborescens fertilization with N resulted in lower P concentrations but only after the third year of fertilization, possibly due to dilution by increased leaf production. Mean trunk diameter growth was significantly higher in the N-fertilized trees than in controls.Mean foliar P concentrations were higher in Podocarpus urbanii and Clethra occidentalis following fertilization with P, but only after two years of fertilization. Trunk diameter growth was greater in the P fertilized plot.Thus growth in some Jamaican montane forest trees was limited by the natural supplies of N and of P.

The headache profile of idiopathic intracranial hypertension.

Abstract: The headache profile of idiopathic intracranial hypertension (IIH, pseudotumour cerebri) has not previously been prospectively studied. We administered a questionnaire to 63 cases at the time of diagnosis. Fifty-eight of the cases had headache and 93% of those with headache reported it to be their most severe ever. Patients characteristically noted a pulsatile headache of gradually increasing intensity that had awakened them. Daily headache occurred in 74% of those reporting headache. Pain in a nerve root distribution or retro-ocular pain with eye movement, uncommon with other headache disorders, help to differentiate this headache syndrome.

Dental Health Diet and Social Status among Central African Foragers and Farmers

Abstract: An oral health survey of African pygmies and Bantu revealed significant contrasts that can be explained by differences in diet, social status, and oral hygiene. Pygmy men have fewer carious lesions and less tooth loss than pygmy women. Ethnographic data suggest that this results from sex differences in eating habits and access to cariogenicfoods. Pygmy "leaders" have much better dental health than "nonleaders." This status difference appears to be explained by social and dietary variables. T HIS ARTICLE PRESENTS THE RESULTS OF A DENTAL HEALTH SURVEY of pygmy hunter-gatherers and Bantu horticulturalists living in the Central African Republic and Zaire (Figure 1). One goal of the study was to test a series of hypotheses we formulated based on previous ethnographic research concerning correlations between a person's sex, social status, and diet. Another purpose of the survey was to collect information for use by archeologists and physical anthropologists who reconstruct prehistoric behavior patterns using dental evidence. By investigating the sociocultural variables that influence the dental health of ethnographically well-documented groups of hunter-gatherers and agriculturalists, we hoped to strengthen the empirical basis for interpreting variation in the dental health of prehistoric populations.